CyberGlossary

Vulnerabilities

Side-Channel Attack

Also known as: Side channel

Definition

An attack that recovers secrets from a system by observing physical or implementation characteristics — timing, power, electromagnetic emissions, caches, acoustic signals — rather than logical flaws.

Side-channel attacks exploit information that leaks through indirect channels while a system performs a legitimate computation: how long an operation takes, how much power it draws, what cache lines it evicts, what radio noise it emits, or even the sound of its components. Classic examples include timing attacks on cryptographic comparisons, differential power analysis (DPA) on smart cards, electromagnetic emanations (TEMPEST), and microarchitectural attacks such as Spectre and Meltdown. Defences combine constant-time algorithms, masking and blinding, isolated execution domains, hardware mitigations (shielding, randomized scheduling, partitioned caches) and architectural changes such as Intel CET or AMD SEV. Effective threat modelling must consider attacker proximity, equipment, and the asset value before choosing mitigations.

Examples

  • Timing differences in MAC comparison revealing key bits.
  • Rowhammer, Spectre, Meltdown — microarchitectural side channels.

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